Modern office equipment such as printers and copiers, are usually designed with an automatic pre-cut paper feeder. Hardly any office machine is equipped with an automatic envelope or other media feeder and provides instead only an automatic feeder for pre-cut paper. Some printers are provided with a slot for manual insertion of media such as envelopes. However, it is labor intensive and time consuming to manually feed a large number of envelopes (or other media) to be printed (or copied).
A difficulty in creating an automatic media feeder lies in a problem of "multiple feed." "Multiple feed" is associated with a bottom feed system and results from the situation where the weight of the stack of media is on the bottom piece thereof that is to be separated from the stack and moved by a feed roller. The friction between the bottom piece and the stack of media above the piece is proportional to the weight of the stack. It is obvious that the greater the weight of the stack of media is, the more the multiple feeding occurs.
U.S. patent application Ser. No. 09/017,248 filed by Mosi Chu, now abandoned, relates to a bottom media feeding device for media of various thicknesses. The media feeding device utilizes a plurality of rollers to separate a bottom piece of paper (or other media) from a stack of paper above it and utilizes a separation means to avoid the problem of "multiple feed". However, such device cannot avoid the problem of the improper orientation of the bottom piece of paper (media).